This invention generally relates to electroplating and electroless plating apparatus and methods.
Electroplating is a common process for depositing a thin film of metal or alloy on a substrate such as, for example, a variety of electronic components and semiconductor chips. In a typical electroplating apparatus or system, the substrate is placed in a suitable electrolyte bath containing ions of a metal to be deposited. The substrate is connected to the negative terminal of a power supply to form a cathode, and a suitable anode is connected to the positive terminal of the power supply. Electrical current flows between the anode and cathode through the electrolyte and metal is deposited on the substrate by an electrochemical reaction.
In many electronic components, it is desirable to deposit the metal film with a uniform thickness across the substrate and with uniformity of composition. However, the electroplating process is relatively complex, and various naturally occurring forces may adversely affect the electroplating process. Most significantly, the electrical current or flux path between the anode and the cathode may spread or curve, making it difficult to achieve uniform electrodeposition.